FaceTime’s a great way for iPhone users to make video calls, but if you’ve ever wondered how much data gets eaten up when you do so, Calling All Geeks ran some numbers.

It turns out, not much. On an older iPhone 4 on a 3G network, a 10 minute call consumed about 30MB of data. That should be improved a little bit on newer phones and the newest version of iOS as well. Our tests with an iPhone 6s put the total right around 25MB for a ten minute call. Regardless, the real takeaway is that FaceTime doesn’t seem to take up a ton of data, so you can use it pretty often without killing your data plan. Of course, you can always keep an eye on your data usage for each app by heading into Settings > Cellular, then scrolling down to the app you’re curious about. Likewise, as reader mrbofus point out, you can just go to your recent calls section and tap the “i” to get the amount of data used in any particular call.